Automakers continue to improve the ride and handling characteristics of the automobile. In some systems, the components of the vehicle were fixed in geometry and characteristics once they were built. The proliferation of less expensive electronics and consumer demand has driven the incorporation of electromechanical dynamic control devices to improve handling and ride characteristics during the operation of the vehicle as conditions change.
Various vehicle dynamic devices such as adjustable suspension units, hydraulic crossover suspension systems, variable volume air suspension springs, or variable stabilizer bars have been contemplated for use in automotive vehicles. Similarly, semi-active and active suspension devices may also be used to improve the ride characteristics of the vehicle. Many of these systems use electronics including sensors, control electronics and various actuators that control vehicle dynamic characteristics.
As an example of a vehicle dynamics device, an interactive vehicle dynamics (IVD) system, may use the brakes independently to assist the driver's ability to turn the motor vehicle. With this system, it is important to first determine whether the vehicle is dynamically stable. Because the various dynamic systems make adjustments to the vehicle characteristics, most systems require an accurate reference at a dynamically stable period of operation. If an accurate determination is not made, the adjustments may not be optimized.
Some systems such as anti-lock brake systems use wheel speeds for determining vehicle stability. While this approach may be suitable for some vehicle dynamic systems, other vehicle dynamic systems require further inputs for a more accurate determination.
It would therefore be desirable to accurately determine whether the vehicle is being operated in dynamically stable position.